As a battery with high voltage and high energy density, a Li ion battery is known, for example. The Li ion battery is a cation-based battery utilizing the reaction between a Li ion and a cathode active material and also the reaction between a Li ion and an anode active material. Meanwhile, as an anion-based battery, a fluoride ion battery utilizing a fluoride ion reaction is known. In Patent Literature 1, for example, a fluoride ion battery having an anode, a cathode, an electrolyte containing a fluoride salt, and a predetermined additive is disclosed.
In claim 16 of Patent Literature 1, R1R2R3S+F− is mentioned as one example of a fluoride salt which can be selected. R1R2R3S+F− has a molar ratio of R1R2R3S+:F31=1:1.